Validation of the histological diagnosis of hydatidiform moles with P57KIP2 immunophenotyping at the University Teaching Hospitals of Kigali and Butare (CHUK, CHUB)

Abstract

Background: The hydatidiform moles remain prevalent in spectrum of gestational trophoblastic diseases (GTDs). In resource-limited settings like Rwanda, their definitive diagnosis relies upon single of histomophological diagnosis in addition to clinical and ultrasonography features. The histomorphology alone was found to have interobserver and intra-observer variability and poor diagnostic reproducibility. The present study aimed at determining the role of histological diagnosis of hydatidiform moles and its validation with p57 immunophenotyping. Methods: This was retrospective observational study embarked at two university teaching hospitals of Kigali and Butare (CHUK, CHUB). Enrolled were all cases of child-bearing women that underwent dilation and curettage or hysterectomy for molar pregnancy between January 2017 and June 2020 and whom histopathological diagnosis was rendered. A review of Hematoxylin &Eosin(H&E) stained slides was performed with subsequent p57 immunostaining after appropriate selection of formalin-fixed paraffin-embedded block (FFPE). Results: Two hundred eleven (211) cases of hydatidiform moles were recorded over three years and six months’ period and 96 (45.9%) cases were all subjected to p57 immunostaining hereby considered as gold standard diagnostic procedure in the diagnosis of hydatidiform moles. As result, the sensitivity and specificity of the histomophological diagnosis of complete hydatidiform mole were estimated at 62.5% and 57.1% respectively with positive and negative likelihood ratio of 0.145 and of 0.54 respectively. Positive and negative predictive value were calculated at 81.8% and 29.3%, respectively. For partial hydatidiform mole sensitivity and specificity of histomophological diagnosis was established at 57.1% and 79.2% whilst positive and negative predictive value counted for 42.9% and 83.8% respectively. The Youden J statistics method was used for accuracy estimation of histomophological diagnosis of hydatidiform mole (HM) and that was 0.196 and 0.336 for both complete and partial hydatidiform moles, respectively. The complete hydatidiform moles were more likely to progress into gestational trophoblastic neoplasia (GTN) as opposed to partial hydatidiform mole (PHM). Conclusion: This study highlighted a need to integrate p57 immunostaining in routine histopathological diagnosis of hydatidiform moles refining the diagnosis of hydatidiform mole.